1. Field of the Invention
The present invention relates to a coating material particularly suitable for an aluminum die casting mold and a method for manufacturing the same. More particularly, the coating material has a multilayer structure in which a Cr(Si) or Ti layer, a Cr(Si)N or Ti(C)N layer, a TiAlN/Cr(SiC)N nano-multilayer, and a Cr(SiC)ON layer are sequentially layered, and wherein sticking resistance, durability, and the like of the mold are improved, and a method for manufacturing the same.
2. Description of the Related Art
Recently, automobile companies have actively conducted studies for securing competitiveness in terms of improving fuel efficiency and regulation of exhaust gas. From this viewpoint, the relative importance in the application of aluminum parts, which provide a weight reduction and, thus, are capable of improving fuel efficiency also tends to increase.
Accordingly, the use of aluminum die casting molds also increases, and high-level physical properties are required for the molds. In particular, because of the use environment in which high load and high impact are continually exerted on the molds, the lifespan of the mold is affected by the materials used to form the molds, the mold design, working conditions, heat treatment and surface treatment, and the like. Further, hardness and physical properties of the molds deteriorate due to generation and growth of heat checking caused by thermal impact, generation of sticking and abrasion caused by molten aluminum used in the molds, a thermal softening phenomenon of the material, and coating of the mold surface caused by operating at high temperatures (reaching about 750° C.), and the like.
Therefore, attempts to prevent deterioration in the lifespan of the mold and maintain the performance thereof have been continuously made. In particular, studies for developing a coating material having excellent physical properties, such as sticking resistance, abrasion resistance, low frictionality, heat resistance, oxidation resistance, and the like have been actively conducted. In particular, such coating materials are developed for application to the interior surface of the molds which come into contact with the molten material to be molded.
For example, in the case of molds, nitride, carbide and the like components, based on titanium (Ti), chromium (Cr), and the like are used as surface protection coating materials for implementing complex performances. In particular, in the case of aluminum die casting molds, chromium nitride (CrN), titanium aluminum nitride (TiAlN), aluminum chromium nitride (AlCrN) and the like are often used as coating materials.
However, the titanium aluminum nitride (TiAlN) coating has such a low thermal resistance. As such, titanium aluminum nitride is not suitable for use as a coating material in an aluminum die casting mold, which is exposed to high-temperature environments of up to 750° C. In particular, such nitrides are problematic in terms of thermal stability, and are prone to deterioration in physical properties and the like when exposed to high-temperature environments.
Further, while aluminum chromium nitride (AlCrN) has relatively excellent thermal resistance compared to titanium aluminum nitride (TiAlN), it has such a low sticking resistance that a molten alloy, such as aluminum and the like, easily adheres to the surface of a mold. As such, there are problems with the use of TiAlN, including a decrease in the lifespan of the mold and deterioration in the quality of a casting product produced therefrom.